Japanese utilities deny problems with steel forgings

Eleven Japanese nuclear operators, including the Tokyo Electric Power Company (Tepco) and Kansai Electric Power Company (Kepco), have notified the Nuclear Regulation Authority (NRA) that all equipment forged at the Japan Casting and Forging Corporation (JCFC) and in use at their NPPs is “sufficiently strong”, according to the Japan Atomic Industrial Forum (Jaif) NRA will now have until the end of the November to decide whether to accept their findings, the statement said.

In 2014, an examination by France’s nuclear regulator, the Autorité de Sûreté Nucléaire (ASN), showed that steel used at the Flamanville-3 EPR under construction in northern France and manufactured at Areva’s Le Creusot forge facility was weaker than expected. Subsequent analysis by ASN indicated that steel from Le Creusot and JCFC might have had significant carbon concentrations.

In June 2016, ASN said some primary bottom heads of steam generators installed at 18 of EDF’s 58 reactors in France could have a significant carbon concentration similar to the anomaly found on the reactor pressure vessel at Flamanville-3. The discovery of that anomaly led ASN and EDF to investigate whether it was also present on other components in operation at existing reactors. The bottom heads at the 18 reactors were manufactured either by Areva’s Le Creusot forge facility or by the JCFC, ASN said.

Jaif said on 2 November that the Japanese utilities had investigated the strength of safety related equipment made with the same forging method as in France. JCFC has manufactured vessel heads for 11 reactor units in Japan – including Takahama-2, Genkai-2, -3 and -4, and Mihama-2 and Genkai-1, which are to be decommissioned. Jaif said no problems were found in those reactors or in units having similar equipment produced by the Japan Steel Works Ltd.

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